Mechanical lead pencil



April 20, 1965 HIROSHI OWADANO 3,179,086

MECHANICAL LEAD PENCIL Filed Feb. 2, 1962 FIG.

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United States Patent 3,179,036 MECHANICAL LEAD PENCIL Hiroshi Owadano, 327 Kinuta-rnachi, Setagaya-ku, Tokyo, Japan Filed Feb. 2, 1962, Ser. No. 170,767 1 Claim. (Cl. 120-12 This invention relates to a single color mechanical lead pencil, and more particularly, to an improved mechanical lead pencil provided with a lead holding sleeve having open ends extending from base to tip throughout the length of the pencil barrel in which protruding and retracting of the sleeve is effected by the short stroke sliding movement.

The conventional lead pencil must be sharpened wasting the material including the lead itself. It is obvious that a great advantage will be obtained if the waste of time and material for sharpening is eliminated by the introduction of the socalled mechanical lead pencil. However, it has never been met with a complete satisfaction since it has several disadvantages to be overcome.

Of the single color mechanical lead pencils of the known types, the most favored ones are as follows: One is of a screw-propelling type in which an end of lead is held by a lead holding sleeve, and the other of a clutch type in which a firm pressure is applied to the side of the lead. In the mechanical lead pencil of the screw type, the elimination of the unstable vibratory motion of the lead point in use has been hardly attained, and the supply of lead should be carried out one by one from the tip of the barrel. In the mechanical lead pencil of the clutch type, on the other hand, there is no firm support for the end of the lead so that it may be easily broken owing to the side pressure. Therefore, it has a serious defect that a lead of either considerable hardness or large size should be employed.

In a known single color mechanical pencil, a screw mechanism was proposed in which the screw mechanism was slidably and coaxially mounted in the barrel. However, it has not lent itself to the practical use because it has not improved either a means for supplying the lead or holding it firmly when in use.

The present invention has for its object the provision of an improved single color mechanical lead pencil of a much more dependable and practical type than those of prior art.

It is, therefore, an object of this invention to provide a mechanical lead pencil in which the lead will not be broken and the length of the lead exposed at the end can be easily adjusted as in screw type mechanical pencils, while, at the same time, a plurality of lead pieces can be supplied from the base end of the lead holding sleeve within the screw mechanism and one of them is fed little by little when the pencil is in use.

It is another object of the invention to provide a mechanical lead pencil of the screw type in which the lead is held firmly and properly in relation to the barrel so that the vibration of the lead can be eliminated when the pencil is in use.

It is another object of the invention to provide a mechanical lead pencil in which a major proportion of material of which this pencil is made can be a light synthetic plastic or wood material together with a less accurate screw mechanism than those of the prior art.

Other objects and further advantages of my invention will become more apparent from the following specification and claim when taken in conjunction with the drawings, in which:

FIG. 1 is a longitudinal sectional view of my improved mechanical lead pencil showing a point of the lead exposed out of the tip.

3,179,086 Patented Apr. 20, 1965 FIG. 2 is a cross-sectional view taken along the line IIII in FIG. 1.

FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1.

FIG. 4 is a cross-sectional view taken along the line IVIV in FIG. 1.

Similar reference numbers indicate corresponding parts throughout the several views and referring now to the same, a barrel 1 comprises a housing for encasing the entire mechanism, and can be made of metal, plastic or some other desirable material. One end is tapered to a tip 5 which is integral with barrel 1. This barrel 1 consists preferably of an upper part 1b with a clip 16 thereon and a lower part 1a, the former being rotatable in relation to the latter. A sleeve 13 is fitted into the interior of the upper part 1b and is held therein by a flange, and it extends into the lower part 1a where it is likewise held by a flange so that parts 1a and 1b can rotate on the sleeve.

A female threaded tube 2, ie a tube 2 provided with a helicoidal groove 12 in the inside surface thereof and which opens out of both ends of the tube 2, is concentrically mounted within the barrel 1 and has a cap 14 over the end within the upper part 1b of the barrel and abuts against a loose ring 21 in the lower part 10!. The inner surface of the barrel 1 is frictionally engaged with the outer surface of the tube 2. A lead holding sleeve 4 is concentrically mounted within the bore of the female threaded tube 2. The lead holding sleeve 4 extends from the base end having the cap 14 thereon to tip 5 throughout the length of the barrel 1 as clearly shown in FIG. 1, and the point of the lead 19 together with the end of the sleeve protrudes out of the constricted tip. However, it is understood that the point of the lead 19 together with the end of the sleeve can be retracted into the interior of the barrel 1 with the retraction of the female threaded tube 2 and the lead holding sleeve 4 when not in use as will be described hereinafter.

The inside diameter of the lead holding sleeve 4 is as large as the size of a lead piece to be used, and it is through the base end 14 of the barrel 1 that the lead should be supplied, not through the tip 5. In general, the lead 19 is shorter than the length of the barrel 1 so that a plurality of lead pieces are fed in succession into the sleeve 4. In other words, the tubular member 4 of my invention could be considered as a magazine for holding several pieces of lead end to end.

The sleeve 4 is provided in one side thereof with an axially extending longitudinal slot 9 corresponding to the length of the female threaded tube 2. One end of the slot 9 is open at the base end of the barrel, and a lead plunger 10 is positioned in the tube 2 and has a pin 11 engaged with the groove of the threaded tube 2 and guided by the slot 9. The lead plunger 10 is almost the same size as the lead and is in the form of T as shown in FIG. 1, and the pin 11 is laterally fixed thereto. The plunger 10 has no lead gripping means.

The sleeve 4 can be made of metal, plastic or some other desirable material, and also may be two-layered, the outer layer being of a frictional material.

The tip of the sleeve 4 has a constricted open end split at 8 to resiliently grip the lead. It is required that the tip 5 and the sleeve 4 should be manufactured so as to fit together as tight as possible. If this fit is too loose, instability of the sleeve may result. However, it will be seen that the manufacture thereof is much easier than for conventional mechanical pencils.

A key 6 is secured to the sleeve 4 in order that the latter will be shifted in the axial direction, but will not be rotated in relation to the barrel 1a. A key groove 7 is provided within the barrel 1a so as to be engaged by the key 6 as shown in FIG. 4. The structure is such that 3 the female threaded tube 2 together with the sleeve 4 can be shifted in the axial direction. As seen in FIG. 2 the portion of the bore within upper part 1b at the base end 'of tube 2 has a square cross-section and the base end of tube 2 has a complementary square shape, so that it will be rotated with the rotatable barrel 1b. Therefore, when the rotatable barrel 1b is rotated in relation to the barrel 1a, the female threaded tube 2 is rotated in relation to the' sleeve 4 with the result that the lead plunger will be shifted along the sleeve 4.

It is not necessary forthe rotatable mechanism to be rotated in anvopposite direction when the pieces of lead are held in the tubular member 4 and fed little by little by the plunger 10. When a new supply of lead is required, however, the lead plunger 10 must be removed from the barrel through the base end thereof by rotation of the rotatable mechanism in the opposite direction and removal of the cap 14. The cap 14 serves as a cover for the ends of both the female threaded tube 2 and the sleeve 4 and also as a push botton to push them slightly when the pencil is in use. However, it is understood that instead of the rotatable barrel 117, an arrangement can be provided so that the cap 14 will rotate the female threaded tube 2.

A spring 15 is provided in the space near the tip of the barrel 1a in order to urge the tubular member 4 upwardly by its action on the key 6 and the female threaded tube through a slip ring and a loose ring 21 with the result that. constant axial contact between the sleeve 4 and the female threaded tube 2 is always maintained whether the tip is protruding or retracted.

However, it is another feature of the invention that the spring 15 serves the following function: the helicoidal groove of the female threaded tube 2 is open at the lower end thereof and the spring 15 urges the loose ring 21 against the end of tube 2, so that if the plunger 10 abuts against the loose ring.21 when the rotatable mechanism is wound too much, the pin 11 of the plunger 10 rotates freely between the lower end of the female threaded tube 2 and the loose ring 21 with the result that the tube 2 will be rotated freely, and further, if the rotatable mechanism is rotated in the opposite direction, the plunger 10 will be urged into the tube 2 by means of the spring.

A key 17 is linked to the clip 16 so as to effect a simultaneous opening and closing therewith through an engagement with a shoulder 18 integral with the female threaded tube 2 in such manner that when the clip 16 opens to disengage the key 17 from the shoulder 18, the

tube 2 and the sleeve 4 are 1nstantly pushed upwardly by the urging of the spring 15 to press the shoulder 18 against the internal shoulder in the barrel 1b just above the shoulder 18, whereby the tip of the member 4 is retracted within the tip 5 of the barrel 1b,

I claim:

A mechanical lead pencil having a barrel tip end' and a base end, which comprises, in combination, a lead holding sleeve having both ends open and extending substantially from the base end to the tip of said barrel, said lead sleeve having a slot opening laterally of said sleeve along the major part of its length, a lead plunger having no lead gripping means slidably mounted in said lead sleeve and having a projection thereon extending through said slot, a cap over the base end of said lead sleeve, said plunger being removable from said sleeve after removing the cap when the plunger is shifted towards the base end of said tube, said lead holding sleeve having a constricted open tip end, said constricted open tip end being exposed and tightly held by the tip end of said barrel when said sleeve protrudes from said barrel, and a rotating mechanism in said barrel comprising a female threaded tube rotatably and slidably mounted in said barrel with the said projection engaged with the thread in said tube, a key mounted in said barrel for only sliding movement axially of said barrel and engaged with said sleeve, a compression spring mounted between said key and said barrel urging said key and sleeve toward the base end of said barrel, said cap being on the base end of said female threaded tube and serving as a push button for pushing said female threaded tube and said lead holding sleeve toward the tip end of said barrel, a projection on the outer peripheral surface of said female threaded tube, said projection being tapered into said tube in the direction toward the tip of said barrel, a link extending through the barrel of said pencil and engaging with said projection on said female threaded tube, a clip adapted to clip the pencil to a shirt pocket or the like pivoted on the outside of the barrel between said link and the base end of said barrel and to which said link is connected, and spring means resiliently urging the end of said clip which is closest to the tip end of the barrel against the barrel, whereby when the clip is pivoted against the action of said spring means the link is withdrawn from engagement with the projection on the female threaded tube.

References Cited by the Examiner UNITED STATES PATENTS 364,303 6/87 Sachs 120 -12 1,585,843 5/26 Fitch 12012 2,938,498 5 Hachmann.

3,101,073 8/63 Baerd l2 X FOREIGN PATENTS 185,896 9/22 Great Britain.

JEROME SCHNALL, Primary Examiner.

JOSEPH D. BEIN, LAWRENCE CHARLES,

Examiners. 

